Monolithic Power Systems Inc. MP28115DQ-LF-P

Overview

MP28115DQ-LF-P from Monolithic Power Systems is a 4A, 1.5MHz synchronous step-down DC/DC converter with internal 60mΩ high- and low-side MOSFETs, adjustable 0.8V–0.9×VIN output, ±1.5% FB voltage accuracy, and integrated soft-start, power-good (POK), and frequency synchronization. It operates from 2.7V–6V input and targets point-of-load regulation in FPGA core supplies and telecom equipment.

For engineers reviewing the MP28115DQ-LF-P datasheet, MP28115DQ-LF-P pinout, MP28115DQ-LF-P application, or MP28115DQ-LF-P equivalent, key selection criteria include its 1.5MHz fixed-frequency peak-current-mode control, hiccup short-circuit protection, thermal shutdown at 150°C, and QFN10 (3mm × 3mm) package with exposed thermal pad for industrial-grade thermal performance.

Technical Context

The MP28115DQ-LF-P implements peak-current-mode PWM control with internal Type II compensation, eliminating external compensation components while supporting loop bandwidth tuning via FB resistor divider. Its transconductance gain of 11.25A/V links COMP voltage to inductor current, simplifying stability design.

It features dual-function EN/SYNC pin enabling both enable/disable control (1.6V/0.4V thresholds) and external clock synchronization (1–2MHz range), plus bootstrap-driven high-side gate drive with dedicated BS pin and open-drain POK output with ±10% VOUT window and 30μs deglitch timer.

Key Specifications

Pinout & Package

MP28115DQ-LF-P is housed in a thermally enhanced 3mm × 3mm, 10-lead QFN package with exposed thermal pad on underside for PCB heat dissipation (θ_JA = 50°C/W, θ_JC = 12°C/W).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar synchronous step-down converter applications.

Compared with MP28115DQ-LF-P, MP28164DQ-LF-Z trades higher current capability for increased static power, while TPS543320RTWR provides superior reference accuracy at the cost of design complexity and missing power-good signaling - making MP28115DQ-LF-P optimal for balanced 4A PoL applications requiring simplicity, thermal efficiency, and system-level fault visibility.

Availability

MP28115DQ-LF-P is available at Aetrix Electronics and suitable for FPGA core supplies, network equipment point-of-load regulation, and LCD TV timing controller power requiring stable component supply, RoHS-compliant packaging, and long-term industrial lifecycle support.

Supply support for MP28115DQ-LF-P includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Monolithic Power Systems (MPS) is a fabless semiconductor company specializing in high-performance analog and power ICs, with design centers in the US, China, and Taiwan, and global manufacturing partnerships.

The MP281xx series targets high-density, high-efficiency DC/DC conversion for portable, telecom, and computing applications - emphasizing integration, thermal performance, and ease of use in space- and reliability-constrained designs.

FAQ

What is the maximum recommended output current for continuous operation?

The MP28115DQ-LF-P is rated for 4A continuous output current under specified conditions: T_A ≤ +85°C, 2-layer PCB with 1 oz copper, and proper thermal pad soldering. Derating is required above +60°C ambient or with inadequate copper area; full 4A load assumes θ_JA ≤ 50°C/W and ≥2 cm² exposed pad copper.

Does MP28115DQ-LF-P require an external Schottky diode?

No - the MP28115DQ-LF-P integrates synchronous rectification with matched 60mΩ high- and low-side MOSFETs, eliminating the need for an external Schottky diode. However, MPS recommends adding one (e.g., B0530) for >2A loads to minimize SW node ringing and slightly improve efficiency at light loads.

How does the EN/SYNC pin function in synchronization mode?

When a 1–2MHz square wave is applied to EN/SYNC, the internal oscillator locks to that frequency within one cycle. The part starts switching after detecting three consecutive valid clock edges. If any ON/OFF pulse exceeds 4μs, the pin reverts to enable/disable mode - ensuring fail-safe behavior during clock loss.

What is the purpose of the BS (Bootstrap) pin, and what capacitor value is recommended?

The BS pin supplies gate drive voltage to the high-side MOSFET via a bootstrap capacitor tied between BS and SW. A 0.1µF X7R ceramic capacitor is recommended - placed as close as possible to the BS and SW pins - to maintain sufficient gate voltage during high-duty-cycle operation and prevent high-side FET dropout.

Can MP28115DQ-LF-P start up into a pre-biased output?

Yes - the IC detects pre-bias at the FB pin and holds both MOSFETs off until the internal soft-start voltage exceeds the sensed output voltage. This prevents reverse current flow and ensures controlled ramp-up even when VOUT is initially charged to 1.2V or higher, critical for hot-swap and multi-rail sequencing.

What is the minimum inductor value recommended for 4A operation?

MPS specifies a 0.47µH to 1µH shielded power inductor with ≥5A saturation current and <10mΩ DCR. For 5V→1.8V/4A at 1.5MHz, a 1µH inductor (e.g., Wurth 744310095) is preferred to limit peak inductor current to ~4.6A and keep ripple below 30% of load current.

Is the exposed thermal pad electrically connected internally?

Yes - the exposed pad is internally connected to GND and must be soldered to a solid PCB ground plane. It serves both thermal and electrical functions: reducing θ_JA by ~25°C/W and providing low-impedance return path for high-frequency switch currents, directly impacting EMI and efficiency.